Voltaire's classic send-up of the philosophy of optimism is both hilarious and deeply depressing. Candide is a frank young German lad whose tutor, Dr. Pangloss, believes that we live in 'the best of all possible worlds'; that is, the reason there is a evil in the world is because there is no other way it could be. Of course Candide encounters all kinds of extravagent evils; he is conscripted involuntarily; his love Cunaganda is disemboweled, raped, forced into being the mistress of various extravagently evil men, Pangloss is hanged, etc., etc., etc. At every turn Candide wavers between despair and ecstasy, attempting to hold to his tutor's belief that this world is the best of all possible worlds. The second older man who befriends him, Martin, is just an emphatic as Pangloss in his belief that everyone in the world is miserable and unlucky. Candide travels three continents, and the coincidences come fast and furious as everyone he's ever known shows up with horror stories.
Neither philosophy allows the possibility of hope; so neither works. Ultimately the only happy person Candide and his companions encounter is someone who 'cultivates his own garden'. Sounds like an injunction to mind your own business.